The present invention relates to an auto tracking apparatus for use in video tape recorders of the helical scan type having a pair of rotary heads which are mounted in diametrically opposite positions of a rotary cylinder.
Various auto tracking apparatus have recently been put to practical use in the field of video tape recorders in order that a magnetic head can accurately scan a video signal-recorded track on reproduction, particularly, speed-varying reproduction such as slow-motion reproduction.
One example of the conventional auto tracking apparatus is disclosed in U.S. Pat. No. 4,451,860 or Japanese Patent Provisional Publication No. 57-66526, the teachings of which involve sampling and holding the detection output of a reproduction high frequency signal at a given point in a field and controlling the head position to keep the level of the detection output to a maximum. However, such prior art apparatus would suffer the problem in that difficulty is encountered to ensure effective tracking control in cases where the following of the track is not parallel to the center line thereof, because the sampling of the detection output signal is performed in terms of only one point per each of a plurality of fields. Thus, a further improvement would be required from the viewpoint of increasing accuracy of the tracing by a reproducing head.